Portable torque and impulse transmitting machine

ABSTRACT

A PORTABLE TORQUE AND IMPULSE TRANSMITTING MACHINE WHEREIN THE POWER TRAIN BETWEEN THE OUTPUT SHAFT OF THE ELECTRIC MOTOR AND THE TOOL IN THE TOOL HOLDER CONTAINS A SAFETY CLUTCH IN SERIES WITH A DISENGAGEABLE COUPLING. THE CLUTCH IS OPERATIVE AT ALL TIMES SO THAT THE TOOL CEASES TO ROTATE WHEN IT ENCOUNTERS A PREDETERMINED RESISTANCE TO ROTATION WHILE THE MOTOR CONTINUES TO OPERATE THE ASSEMBLY WHICH TRANSMITS TO THE TOOL AXIALLY ORIENTED IMPULSES TO DRIVE IT INTO A ROCK OR THE LIKE. THE COUPLING IS CONTROLLED BY A SWITCHING MEMBER WHICH IS PLACED SO CLOSED TO AN AUXILIARY HANDLE THAT THE HAND WHICH GRIPS THE AUXILIARY HANDLE CAN REACH THE SWITCHING MEMBER WITHOUT APPRECIABLY RELAXING THE GRIP ON THE HANDLE. THE AUXILIARY HANDLE CAN BE COUPLED TOTHE SWITCHING MEMBER IN SUCH A WAY THAT THE HAND WHICH GRIPS THE HANDLE CAN ENGAGE OR DISENGAGE THE COUPLING IN RESPONSE TO ROTATION OF THE HANDLE.   D R A W I N G

Much 13, 1973 n. www ETAL 307299269 PRTBLE TORQUE AND INPULSE TRANSHITTING MACHINE Filed Dec. 21, 1970 5 Sheets-Sheet l March 13, 1973 K. WANNER ETAL 3,720,269

PORTABLE TOHQUE AND IMPULSE TRANSKITTING MACHINE Filed Dec. 21, 1970 5 sheets-sneer a /fvrfwra/Ps y March 13, 1973 K. WANNER ETAL 3,720,269

PORTABLE TORQUE AND IMIULSE TRANSMITTING MACHINE Filed Dec. 21, 1970 5 Sheets-Sheet I5 March 13, 1973 K. wANNr-:R E'rAL PORTABLE TORQUE AND IMPULSE TRANSMITTING MACHINE Filed Dec. 21, 1970 5 Sheets-Sheet 4 March 13, 1973 K. wANNER ETAL 3,720,269

PORTABLE TORQUE AND IMPULSE TRANSIIITTING MACHINE A Filed Dec. 21, 1970 5 sheets-Sheet 5 ffieff/lrmfyfy Fig. 8

'United States Patent O U.S. Cl. 173-48 13 Claims ABSTRACT F THE DISCLOSURE A portable torque and impulse transmitting machine wherein the power train between the output shaft of the electric motor and the tool in the tool holder contains a safety clutch in series with a disengageable coupling. The clutch is operative at all times so that the tool ceases to rotate when it encounters a predetermined resistance to rotation While the motor continues to operate the assembly which transmits to the tool axially oriented impulses to drive it into a rock or the like. The coupling is controlled by a switching member which is placed so close to an auxiliary handle that the hand which grips the auxiliary handle can reach the switching member without appreciably relaxing the grip on the handle. The auxiliary handle can be coupled to the switching member in such a way that the hand which grips the handle can engage or disengage the coupling in response to rotation of the handle.

BACKGROUND OF THE INVENTION The present invention relates to a portable torque and impulse transmitting machine, such as a hammer drill, which can be used for the drilling of holes in rock, concrete or for analogous purposes. More particularly, the invention relates to improvements in portable torque and impulse transmitting machines of the type wherein the tool can receive axially oriented impulses to facilitate its penetration into a rock or the like While the tool rotates or while the transmission of torque from a prime mover to the tool is interrupted.

In presently known machines of the above outlined character, the power train which transmits torque from the prime mover to the tool includes a coupling which can act as a safety clutch to interrupt the transmission of torque at the will of the operator. The clutch is controlled by an actuator which can be moved between three different positions in the iirst of which the clutch is disengaged so that the prime mover cannot rotate the tool, in the second of which the clutch is permanently engaged and transmits torque irrespective of the magnitude of resistance which the tool offers to rotation, and in the third of which the coupling acts as a safety or overload clutch and permits the tool to come to a standstill when its resistance to rotation exceeds a predetermined value. When the actuator assumes its rst position, the tool merely receives axially oriented impulses but does not rotate; in the second position of the actuator, the tool must rotate as long as the prime mover is in operation and the tool also receives recurrent axially oriented impulses; in the third position of the actuator, the tool normally rotates and simultaneously receives axial impulses but can cease to rotate when it meets a predetermined maximum resistance to rotation.

A drawback of machines which embody the just described actuator is that the actuator can be accidentally 3,720,269 Patented Mar. 13, 1973 moved from its third position whereby the machine is likely to be damaged if the tool encounters excessive resistance to rotation. Furthermore, at least one hand of the operator must be removed from the handle or housing whenever the operator wishes to change the setting of the actuator.

SUMMARY OF THE INVENTION An object of the invention is to provide a torque and impulse transmitting machine wherein the parts are invariably protected from excessive stresses and which can be readily converted from operation with transmission of impulses to operation with simultaneous transmission of torque and impulses, or vice versa.

Another object of the invention is to provide the machine with novel means for changing from operation with transmission of impulses to operation with simultaneous transmission of torque and impulses, or vice versa.

A further object of the invention is to provide a torque and impulse transmitting machine whose operation can be regulated without necessitating removal of one hand from the handle or housing of the machine.

An additional object of the invention is to provide a novel torque-transmitting power train between the prime mover and the tool in a torque and impulse transmitting machine.

Still another object of the invention is to provide a novel safety clutch for use in a torque and impulse transmitting machine.

A further object of the invention is to provide a torque and impulse transmitting machine with a safety clutch which is operative at all times so that a careless or ignorant operator is unable to damage the machine by causing the tool to rotate under circumstances when the material which is to be formed with a bore or hole offers excessive resistance to such rotation.

The invention is embodied in a manually operated torque and impulse transmitting machine which cornprises a portable housing including a preferably sleevelike forwardly extending tool holder for a rotary tool, such as a rock drill, a prime mover which preferably includes an electric motor mounted in the housing and having a rotary output member, an impeller assembly mounted in the housing and including an impeller which is coaxial with the tool holder and is reciprocable in the housing into and from impulse-transmitting engagement with the tool in the tool holder, a first power train mounted in the housing and preferably including a crank drive arranged to effect reciprocatory movements of the impeller in response to rotation of the output member, and a second power train mounted in the housing to transmit torque from the output member to the tool in the tool holder.

The second power train comprises an overload or safety clutch having iirst and second clutch elements which are disengaged from each other to thereby terminate the transmission of torque from the output member to the tool in the tool holder when the resistance which the tool oiers to rotation exceeds a predetermined maximum value, and a coupling which is in series with the clutch and has a first portion receiving torque from the output shaft and a second portion for transmitting torque to the tool in the tool holder. One portion of the coupling is movable to and from an operative position in which the tirst portion drives the second portion. The machine further comprises switching means which is operative to move the one portion of the coupling to and from the operative position. Since the clutch is in series with the coupling, the operator cannot inuence the operation of the clutch so that the tool cannot be rotated at a time when its resistance -to rotation exceeds the aforementioned maximum permissible value.

'Ihe novel features which are considered as characteristie of the invention are set forth in particular in the appended claims. The improved machine itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a fragmentary partly side elevational and partly longitudinal vertical sectional view of a torque and impulse transmitting machine which embodies one form of the invention;

FIG. 2 is a fragmentary side elevational View of a second machine;

FIG. 3 is a bottom plan view as seen in the direction of arrow III in FIG. 2;

FIG. 4 is a fragmentary side elevational view of a third machine;

FIG. 5 is a bottom plan view as seen in the direction of arrow V in FIG. 4;

FIG. 6 is a fragmentary partly side elevational and partly vertical sectional view of a fourth machine;

FIG. 7 is a fragmentary end elevational view as seen in the direction of arrow VII in FIG. 6, with certain parts shown in vertical section; and

FIG. 8 is a fragmentary side elevational view of a fifth machine.

DESCRIPTION OF THE., PREFERRED EMBODIMENTS FIG. 1 illustrates a torque and impulse transmitting machine which is particularly suited for drilling holes in rock, concrete and like materials. The machine comprises a composite housing including rst housing 1 for a prime mover preferably including an electric motor 1a whose output shaft 1b carries a pinion 10. The rear portion of the housing 1 is integral with or connected to a main handle 2 which receives one end of a cable 3 serving to connect the motor 1a with a source of energy, not shown. A master switch (not shown) in the motor circuit can be closed by a trigger 4 in the handle 2. When the machine is in use, the workpiece to be treated is located to the left of the motor housing 1, i.e., opposite the handle 2.

The upper portion of the motor housing 1 is connected with a second housing 5 which constitutes a gear case and extends forwardly, i.e., away from the main handle 2. The upper portion of the gear case 5 is connected to or integral with an impeller housing 6 without any partition therebetween. A sleeve-like tool holder 7 of the composite housing is connected to the front part of the irnpeller housing 6 and to a downwardly extending auxiliary or stabilizing handle 8. A selector housing 9 is provided on or connected with the lower left-hand portion of the gear case 5 in close or immediate proximity of the auxiliary handle 8.

The pinion 10 on the output shaft 1b of the motor 1a meshes with a gear 12 which is rotatable in needle bearings 11 provided therefor in the gear case 5. The upper face of the gear 12 has an eccentric crank pin 13 which is surrounded by a needle bearing 14 and extends into the slot of a reciprocable carriage 15. The latter extends transversely of and is preferably integral with a cylinder 16 in the impeller housing 5. The cylinder 16 is reciprocable in suitable guide means (not shown) provided in the housing 6. A piston 17 is reciprocable in and divides the interior of the cylinder 16 into a rear chamber 22 and a front chamber 21. The piston rod 18 of the piston 17 constitutes an impeller or ram and extends forwardly through the front chamber 21 and beyond a sleeve-like guide portion 19 of the cylinder 16. The shell of the cylinder 16 is provided with openings 20 lwhich connect the chamber 21 and/or 22 with the atmosphere in certain axial positions of the piston 17. When the piston 17 is moved to its foremost position, the openings 20 connect the rear chamber 22 with the atmosphere. The parts 16-22 constitute and impeller assembly and the parts 10-15 constitute a rst power train serving to reciprocate the impeller 18 axially of the tool holder 7 whereby the impeller transmits to the tool in the tool holder recurrent axially oriented impulses when the circuit of the motor 1a is completed by the trigger 4.

Ihe aforementioned gear 12 has a downwardly extending integral shaft 12a which is connected to or integral with a pinion 23. The latter meshes with a ring gear 24 of a hollow motion transmitting member 25 which is rotatable in needle bearings 26 provided in the gear case 5. The member 25 serves as a support or bearing for two apertured disks 27 and 28 respectively having hubs 29 and 30 which extend toward each other. A portion of the hub 30 is telescoped into the hub 29. The disks 27, 28 are respectively disposed at the upper and lower axial ends of the motion transmitting member 25 and their hubs 29, 30 form a sleeve in the interior of the member 25; thus, only the external (circumferential) surface of the member 25 remains exposed. Such external surface is partially received in the needle bearing 26 and the remaining part thereof forms the ring gear 24. The disks 27, 28 and their hubs 29, 30 together form a spool whose core (hub 29, 30) is surrounded by the member 25 and whose flanges (disks 27, 28) are adjacent to the axial ends of the member 25.

The bores of the hubs 29, 30 receive a rotary shaft 31 the upper portion of which is formed with an integral bevel gear 32 extending into the impeller housing 6. The bevel gear 32 meshes with a second bevel gear 33 having a forwardly extending hub 34 which is coaxial with the tool holder 7. The bevel gear 33 and its hub 34 serve to transmit torque to the tool in the tool holder 7.

The lower end portion of the shaft 31 is formed with axially parallel teeth 35 meshing with the internal teeth of a coupling sleeve 36 which is movable axially of the shaft 31. The upper portion 37 of the sleeve 36 constitutes a disk whose upper end face is provided with claws 38 movable into engagement with claws 39 provided on the lower end face of the lower disk 28. The lower end portion of the coupling sleeve 36 has a cylindrical peripheral surface which is provided with a circumferential groove 40 for an elastic ring 41. An adjusting sleeve or selector rotatably surrounds the coupling sleeve 36- and abuts against the disk 37 and against the ring 41. An extension 43 of the adjusting sleeve 42 extends into an elongated groove 44 provided in the adjacent wall of the selector housing 9 so that the sleeve 43 is held against rotation. The cylindrical external surface of the adjusting sleeve l42 is formed with a steep thread 45 having several convolutions and meshing with a similar thread 46 of a switching member or actuator 47. The switching member 4'7 has a hollow shaft 48 which is coaxial with the shaft 31 and sleeves 36, `42 and extends into an annular bore or recess 49 of the selector housing 9. The switching member 47 is held against axial movement by an elastic split ring 50 and a shoulder which abuts against a complementary shoulder of the housing 9. The bore 49 accommodates a sealing element 51 which prevents entry of foreign matter along the peripheral surface of the shaft 48. The coupling sleeve 36 and the claws 39 of the disk 28 constitute a coupling which forms part of the torquetransmitting power train between the output shaft 1b and the tool in the tool holder 7. The coupling can be disengaged by rotating the switching member 47 to thereby move the sleeve 36 downwardly and away from the illustrated operative position in which the claws 38 engage with the claws 39.

The motion transmitting member 25 is formed with an annulus of axially parallel bores or holes 52 which are equidistant from the axis of the shaft 31 and from each other. The disks 28, 29 have axially parallel holes or bores 53 whose centers are located on a circle having the same diameter as the circle including the axes of the holes 52. The distances between neighboring holes '53 are the same as those between the holes 52. The diameters of the holes 53 are somewhat smaller than those of the holes '52. Each hole 52 accommodates with a small clearance two steel balls 54 which are biased apart by a helical spring 55 so that they bear against the disks 27 and 28. Thus, when a hole 53 in the disk 28 or 29 moves into registry with a -hole 52, the corresponding ball 54 snaps into such hole 53. Since the diameter of each hole 53 is smaller than that of a hole 52, only a small portion (less than half) of a ball 54 can be caused to penetrate into the hole 53. The parts 25-30 and 52-55 constitute a safety or overload clutch which forms part of the torquetransmitting power train and is in series with the coupling 36-39. The user of the machine cannot inuence the operation of the safety clutch.

The operation:

The trigger 4 can be depressed to complete the circuit of the motor 1a whereby the pinion 10 on the output shaft 1b drives the gear 12. The eccentric crank pin 13 causes the cylinder 16 to move back and forth whereby the cylinder reciprocates the piston 17 and its impeller 18. The piston 17 has some freedom of axial movement with reference to the cylinder 16'due to the provision of air cushions in the chambers 21 and 22. The impeller 18 transmits axially oriented impulses to a tool (not shown) in the tool holder 7.

The pinion 23 rotates with the gear 12 and drives the ring gear 24 of the motion transmitting member 25 which in turn drives the disks. 27, 28 by way of the balls 54. These balls and the associated springs 55 form part of the aforementioned safety clutch or overload clutch which permits the member 25 to rotate relative to the disks 27, 28 when the tool in the holder 7 offers an excessive resistance to rotation. The claws 39 of the lower disk 28 engage the claws 38 of the coupling sleeve 26 which rotates the shaft 31 by way of the teeth 35. The shaft 31 drives the bevel gear 3-2 which rotates the hub 34 and the tool in the hol-der 7 by way of the bevel gear 33.

When the switching member 47 is moved to a second angular position, the mating steep threads 46, 45 move the adjusting sleeve 42 axially downwardly. The adjusting sleeve 42 entrains the coupling sleeve 36 to thereby disengage the claws 38 from the claws 39 on the disk 28. The disk 28 continues to rotate in response to rotation of the motion transmitting member 25 but it cannot transmit torque to the shaft 31 so that the tool in the holder 7 ceases to rotate.

The auxiliary handle 8 has an upper end portion 56 which is in clamping engagement with the tool holder 7. The upper end portion 56 is located above a cylindrical intermediate portion 57 of the handle 8 which is separated from a handgrip portion '58 by a flange 59. The switching member 47 is placed so close to the handgrip portion 58 that a ringer of the hand which grips the portion 58 can readily move the member 47 between its two positions to thereby establish or terminate the torquetransmitting connection between the motion transmitting member 25 and the tool in the holder 7.

Referring to FIGS. 2 and 3, the handgrip portion 158 of a modified auxiliary handle 108 is separated from the upper part of the cylindrical portion 157 by a ange 159 which is provided with a ring gear 160 meshing with a gear segment 161 on the switching member 147. The portions 158, 159 are rotatable on the cylindrical portion 157 by that'hand which grips the portion 158 so that the operator can readily change the angular position of the switching member 147 without even removing a single linger from the portion 158. Otherwise, the construction of the machine shown in FIGS. 2 and 3 is preferably identical with that of the machine shown in FIG. 1. The

portions 157, 159 can carry cooperating detent means to yieldably hold the gear in one or both end positions. Such detent means can be mounted in the housing 9 to yieldably hold the switching member 147 in one or both end positions.

The machine of FIGS. 4 and S has a different auxiliary handle 208 wherein the portions 257, 258, 259 are respectively analogous to the portions 157, 158, 159 of FIGS. 2 and 3. The difference is that the gears 160, 161 are replaced by a pin-and-slot connection including an inclined slot 260 in the flange 259 and a pin 261 provided on an extension of the switching member 247. The portions 258, 259 are rotatable with reference to the portion 257 to enable the hand which grips the portion 258 to change the angular position of the switching member 247.

The auxiliary handles 108, 208 of FIGS. 2-5 enable the operator to rapidly adjust the switching member 147 or 247 without even temporarily relaxing the hold on the portion 158 or 258. Thus, the operator can rapidly and conveniently shift from simultaneous operation with impeller and transmission of torque to operation with the impeller alone, or vice versa. The handle 208 of FIGS. 4 and 5 is simpler than the handle 108 because the switching member 247 and flange 259 need not be provided with mating teeth. In assembling the handle 208, the person in charge slips the portions 258, 259 onto the por tion 257 in such angular position that the pin 261 enters the slot 260. The portions 258, 259 are thereupon rotatably secured to the portion 257 in such a way that they are held against axial movement. The assembly of the handle 108 is simpler because the portions 158, 159 can be mounted on the portion 157 in any angular portion, as long as the gear segment 161 .moves into mesh with the gear 160.

As stated before, the handle 108 can be provided with detent means which yieldably holds the portions 158, 1'59 in at least one of the two positions which correspond to the two end positions of the switching member 147. Similar detent means can be employed in the handle 208 of FIGS. 4 and 5, Furthermore, the tool holder 7 of the machine shown in FIG. 1, FIGS. 22-3 or FIGS. L5 can be provided with stop means to locate the clamping portion 56, 156 or 256 in an optimum axial position so as to insure that the switching member 47 is within reach of a nger on that hand which grips the portion 58, that the gear 160 is in proper mesh with the gear segment 161, or that the pin 261 can enter the slot 260 when the portions 58-59 or 158-159 or 258-259 are respectively slipped onto the portions 57, =157, 2:57.

FIGS. 6 and 7 show a machine which constitutes a modification of the structure shown in FIGS. 4 and 5 and embodies detent means for the auxiliary handle. The tool holder 307 is provided with a wide -circumferentially complete grove 307' bounded by a cylindrical surface and two annular shoulders. The clamping portion 356 of the auxiliary handle 308 has two separable substantially semicircular parts 356a, 356b which extend into the groove 307. The aforementioned annular shoulders of the tool holder 307 insure that the clamping portion 356 is held against axial movement. The parts 356a, 356b are separably secured to each other by threaded fasteners 356e.

'Ihe part 356b of the clamping portion 356 is rigidly connected to or integral with an intermediate portion 357 of the auxiliary handle 308 which further comprises a handgrip portion 358 and a flange 359 having a slot (not shown) for the pin 361 of the switching member 347. The intermediate portion 357 has an axial bore 370 which includes a smaller-diameter portion extending through the part 356b and communicating with the groove 307'. The maximum-diameter portion 371 of the bore 370 extends to the lower end of the intermediate portion 357 and is accessible when the handle 308 is taken part. The median portion of the bore 370 is tapped, as at 372, to mesh with an externally threaded plug 376 serving to stress a helical spring 375 which biases a spherical detent element 374. The latter extends into a concave socket or notch 373 machined into the cylindrical surface in the innermost part of the groove 307 when the auxiliary handle 308 assumes a predetermined angular position with reference to the tool holder 207, namely, that position in which the pin 361 of the switching member 347 can extend into the slot of the flange 359.

It will be seen that the structure shown in FIGS. 6 and 7 insures that the auxiliary handle 308 is properly positoned by the groove 307 as considered in the axial direction of the tool holder 307, and that the detent means including the element 374 insures that the handle 308 can be yieldably held in such angular position with reference to the tool holder that, when the handgrip portion 358 is rotatably secured to the intermediate portion 357, the slot of the flange 359 (which can rotate with the handgrip portion) can receive the pin 361.

FIG. 8 shows a portion of a torque and impulse transmitting machine wherein the auxiliary handle 407 is coaxial with and directly or indirectly connected to a rotary switching member 447 so that the latter can be rotated in response to turning of the handle 408. This handle can actuate the switching member 447 by Way of one or more intermediate parts, not shown.

Without further analysis, the foregoing will so 4fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of our contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims:

We claim:

1. A manually operated torque and impulse transmitting machine, comprising a portable housing including a tool holder for a rotary tool; an electric motor mounted in said housing and having a rotary output member; an impeller assembly mounted in said housing and including an impeller coaxial with said tool holder and reciprocable into and from impulse-transmitting engagement with the tool in said tool holder, a cylinder reciprocably mounted in said housing coaxial with said impeller, and a piston reciprocably received in said cylinder and rigid with said impeller, said cylinder having two air-filled chambers flanking said piston so that the air in said chambers constitutes two cushions which enables said piston and said impeller to perform at least some axial movement with reference to said cylinder, at least one of said chambers being in communication with the surrounding atmosphere in predetermined axial positions of said piston with reference to said cylinder; a first power train mounted in said housing and arranged to effect reciprocatory movement of said impeller in response to rotation of said output member, said first power train including a crank drive for said cylinder; a second power train mounted in said housing and arranged to transmit torque to the tool in said holder, comprising an overload clutch having first and second clutch elements which are disengaged from each other to thereby terminate the transmission of torque from said output member to the tool in said holder when the resistance which the tool offers to rotation exceeds a predetermined value, and a coupling in series with said clutch and having a first portion receiving torque from said output member and a second portion for transmitting torque to the tool in said holder, one of said portions being movable to and from an operative position in which said first portion drives said second portion; and switching means operative to move said one portion of the clutch to and from said operative position.

2. A machine as defined in claim 1, wherein said portions of said coupling are rotatable about a common axis and said one portion is movable axially to and from said operati-ve position, the operation of said clutch being independent from movements of said one coupling portion to and from said operative position.

3. A machine as defined in claim 1, further comprising a handle provided on said housing in such close proximity of said switching means that the latter can be operated by the hand `which grips said handle.

4. A machine as defined in claim 3, further comprising a second handle provided on said housing to be gripped by one of the operators hands While the other hand grips said first mentioned handle.

5. A machine as defined in claim 1, further comprising a handle provided on said housing and having a movable handgrip portion, and means for operating said switching means in response to movement of said handgrip portion.

6. A machine as dened in claim 1, further comprising a handle provided on said housing, said handle being coaxial with said coupling portions.

7. A machine as defined in claim 6r, wherein said switching means is coaxial with and rotatable by said handle between first and second positions which respectively correspond to said operative position and an inoperative position of said one coupling portion.

8. A manually operated torque and impulse transmitting machine, comprising a portable housing including a tool holder for a rotary tool; a prime mover mounted in said housing and having a rotary output member; an impeller assembly mounted in said housing and including an impeller coaxial with said tool holder and reciprocable into and from impulse-transmitting engagement with the tool in said holder; a first power train mounted in said housing and arranged to effect reciprocatory movements of said impeller in response to rotation of said output member; a second power train mounted in said housing and arranged to transmit torque to the tool in said holder, comprising an overload clutch having first and second clutch elements which are disengaged from each other to thereby terminate the transmission of torque from said output member to the tool in said holder when the resistance which tool offers to rotation exceeds a predetermined value, said clutch elements being rotatable about a common axis and having adjacent surfaces provided with registering bores including at least one smaller-diameter bore in yone said surfaces and at least one larger-diameter bore in the other surface, said clutch further comprising a torque transmitting element received in said larger-diameter bore and having a spherical portion 'which is receivable in the smaller-diameter bore, and means for biasing said spherical portion into said smaller-diameter bore with a force which suices to cause rotation of said elements as a unit until the resistance which the tool offers to rotation reaches said value whereupon said spherical portion returns into said larger-diameter bore against the opposition of said biasing means so that one of said elements can rotate with reference to the other element, and a coupling in series with said clutch and having a first portion receiving torque from said output member and a second portion for transmitting torque to the tool in said tool holder, one of said portions being movable to and from an operative position in which lsaid first portion drives said second portion; and switching means operative to move said one portion of the clutch to and from said operative position.

9. A manually operated torque and impulse transmitting machine comprising a portable housing including a tool holder for a rotary tool; a prime mover mounted in said housing and having a rotary output member; an impeller assembly mounted in said housing and including an impeller coaxial with said tool holder and reciprocable into and from impulse-transmitting engagement with the tool in said holder; a first power train mounted in said housing and arranged to effect reciprocatory movements of said impeller in response to rotation of said output member; a second power train mounted in said housing and arranged to transmit torque to the tool in said holder, comprising an overload clutch having first and second clutch elements which are disengaged from each other to thereby terminate the transmission of torque from said output member to the tool in said holder when the resistance which the tool oters to rotation exceeds a predetermined value, and a coupling in series with said clutch and having a rst portion receiving torque from said output member and a second portion for transmitting torque to the tool in said tool holder, one of said portions being movable to and from an operative position in which said first portion drives said second portion; switching means operative to move said one portion of the clutch to and from said operative position, said switching means being rotatable between rst and second positions which respectively correspond to said operative position and an inner inoperative position of said one coupling portion; a handle provided on said housing and having a movable handgrip portion; and means for operating said switching means in response to movement of said handgrip portion, said operating means comprising mating gears provided on said handgrip portion and on said switching means.

10. A manually operated torque and impulse transmitting machine, comprising a portable housing including a tool holder for a rotary tool; a prime mover mounted in said housing and having a rotary output member; an impeller assembly mounted in said housing and including an impeller coaxial with said tool holder and reciprocable into and from impulse-transmitting engagement with the tool in said holder; a rst power train mounted in said housing and arranged to effect reciprocatory movement of said impeller in response to rotation of said output member; a second power train mounted in said housing and arranged to transmit torque to the tool in said holder, comprising an overload clutch having rst and second clutch elements which are disengaged from each other to thereby terminate the transmission of torque from said output member to the tool in said holder, when the resistance which the tool offers to rotation exceeds a predetermined value, and a coupling in series with said clutch and having a first portion receiving torque from said output member and a second portion for transmitting torque to the tool in said holder, one of said portions being movable to and from an operative position in which said rst portion drives said second portion; switching means operative to move said one portion of the clutch to and from said operative position, said switching means being rotatable between rst and second positions which respectively correspond to said operative position and an inoperative position of said one coupling portion; a handle provided on said housing and having a movable handgrip portion; and means for operating said switch means in response to movement of said handle portion, said operating means comprising a pin and slot connection between said handgrip portion and said switching means.

11. A machine as defined in claim 10, wherein said Connection comprises a slot provided in a substantially disk-shaped part of said handgrip portion and a pin provided on said switching means and extending into said slot to rotate the switching means in response to movement of said handgrip portion.

12. A manually operated torque and impulse transmitting machine, comprising a portable housing including a tool holder for a rotary tool; a prime mover mounted in said housing and having a rotary output member; an impeller assembly mounted in said housing and including an impeller coaxial with said tool holder and reciprocable into and from impulse-transmitting engagement with the tool in said tool holder; a first power train mounted in said housing and arranged to etfect reciprocatory movements of said impeller in response to rotation of said output member; a second power train .mounted in said housing and arranged to transmit torque to the tool in said holder, comprising an overload clutch having first and second clutch elements which are disengaged from each other to thereby terminate the transmission of torque from said output member to the tool in said holder when the resistance which the tool offers to rotation exceeds a predetermined value, and a coupling in series with said clutch and having a first portion receiving torque from said output member and a second portion for transmitting torque from the tool in said holder, one of said portions being movable to and from an operative position in which said iirst portion drives said second portion; switching means operative to move said one portion of the clutch to and from said operative position; a handle provided on said housing and having a movable handgrip portion which is rotatable with reference to said housing and which is located forwardly of said second power train; and means for operating said switching means in response to movement of said handgrip portion.

13. A machine as defined in claim 12, further comprising detent means for yieldably holding said handgrip portion in an angular position corresponding to the operative position of said one coupling portion.

References Cited UNITED STATES PATENTS 3,430,708 3/1969 Miller 173-123 1,338,019 4/1920 Jackson 173-48 2,223,727 12/1940 Horner 173-109 2,602,426 7/ 1952 Galvez 173-109 3,203,490 8/1965 McCarty et al 173-109 3,456,740 7/11969 `Paule et al. 1173-109 I AMES A. LEPPINK, Primary Examiner U.S. Cl. X.R. 173-109, 123, 139 

